Steven Pinker -- How the Mind Works - Hampshire High Italian ...

The Mind's Eye 245lished a list of straight lines in nature, recently reprinted in Harper'smagazine:line along the top of a breaking wave; distant edge of a prairie; paths ofhard rain and hail, snow-covered fields; patterns in crystals; lines of whitequartz in a granite surface; icicles, stalactites, stalagmites; surface of acalm lake; markings on zebras and tigers; bill of a duck; legs of a sandpiper;angle of migrating birds; dive of a raptor; new frond of a fem;spikes of a cactus; trunks of young, fast-growing trees; pine needles; silkstrands ivoven by spiders; cracks in the surface of ice; strata of metamorphicrock, sides of a volcano; wisp of windblown altocumulus clouds;inside edge of a half-moon.Some of these are arguable, and others will do a shape guesser moreharm than good, ('llie horizon of a lake or prairie and the edge of a halfmoondo not come from lines in the world.) But the point is right. Manylaws of the world give it nice, anaiyzable shapes. Motion, tension, andgravity make straight lines. Gravity makes right angles. Cohesion makessmooth contours. Organisms that move evolve to be symmetrical. Naturalselection shapes their body parts into tools, duplicating the humanengineer's demand for well-machined parts. Large surfaces collect patternswith roughly equal sizes, shapes, and spacing: cracks, leaves, pebbles,sand, ripples, needles. Not only are the seemingly carpentered andwallpapered parts of the world the parts most recoverable by a shapeanalyzer; they are the parts most worth recovering. 'ITiey are the telltalesigns of potent forces that fill and shape the environment at hand, andare more worthy of attention than heaps of random detritus,Even the best line analyzer is equipped only for a cartoon world. Surfacesare not just bounded by lines; they are composed of material. Oursense of lightness and color is a way of assaying materials. We avoid bitinginto a plaster apple because the color tips us off that it is not made offruit flesh.Analyzing matter from the light it reflects is a job for a reflectancespecialist. Different kinds of matter reflect back different wavelengths oflight in different amounts. (To keep things simple, I'll stay in blackand white; color is, roughly, the same problem multiplied by three.)